#include <stdio.h>
/* 全局变量声明 */
int a = 20;
int sum(int a, int b);
int main ()
{
	/* 在主函数中的局部变量声明 */
	int a = 10;
	int b = 20;
	int c = 0;
	printf ("value of a in main() = %d\n",  a);
	printf ("value of b in main() = %d\n",  b);
	c = sum( 11, 22);
	printf ("value of c in main() = %d\n",  c);
	return 0;
}
/* 添加两个整数的函数 */
int sum(int a, int b)
{
	printf ("value of a in sum() = %d\n",  a);
	printf ("value of b in sum() = %d\n",  b);
	return a + b;
}

